1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device of a so-called reflection type which performs a display using a reflection light of an incident external light or of an active matrix type which combines a transmission type and a reflection type.
2. Description of the Related Art
In a liquid crystal display device of an active matrix type, regions which are surrounded by gate signal lines which are extended in the x direction and are arranged in parallel in the y direction and drain signal lines which are extended in the y direction and are arranged in the x direction in parallel on a liquid-crystal-side surface of one of respective substrates which are arranged in an opposed manner while inserting the liquid crystal therebetween are defined as pixel regions, wherein each pixel region is provided with a thin film transistor which is driven with the supply of scanning signals from the gate signal line at one side and a pixel electrode to which video signals from the drain signal line at one side are supplied through the thin film transistor.
These pixel electrodes generate an electric field having an intensity which corresponds to the video signals between the pixel electrodes and a counter electrode formed on a liquid-crystal-side surface of the other substrate so as to control the light transmittivity of the liquid crystal.
As one of these liquid crystal display devices, there has been known a so-called reflection-type liquid crystal display device in which pixel electrodes are constituted of material (for example, aluminum) which reflects an external light incident through the other substrate (the substrate positioned at a viewer's side).
Further, there has been also known a liquid crystal display device in which island-like material layers are positioned in a scattered manner at lower layer sides of pixel electrodes and protruding portions of the material layers are exposed on surfaces of the pixel electrodes so that the reflection characteristics which are uniform and exhibit the favorable light scattering property can be obtained (see Japanese Laid-open Patent Publication 98375/2000, Japanese Laid-open Patent Publication 337961/1999).
However, in the liquid crystal display devices having such constitutions, all of the island-like material layers which are formed at the lower layer sides of the pixel electrodes have the same shape (including the similar shape) when viewed in a plan view so that all of the side surfaces of the protrusions which are exposed from the surfaces of the pixel electrodes due to respective material layers have the same taper angle.
Accordingly, it has been pointed out that light beams which are reflected on the side surfaces of the protruding portions of the pixel electrodes interfere with each other so that the interference light generated by such an interference suppresses the enhancement of the display quality.